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skeletal systems

...substantial endoskeletal units in arthropods. The fibres are not united to the cuticle and are not shed during molting; rather, they grow with the body. A massive and compact endo
sternite (internal
sternite), formed by connective-tissue fibres, frequently lies below the gut and above the nerve cord. In
Limulus, the horseshoe crab, muscles from the anterior margin of the coxa (the leg...